This invention relates to rotary engines and namely gas turbines for producing shaft power with minimal thrust (jet) while utilizing an internal combustion cycle, the Brayton Cycle, in which heat is added to a compressed working fluid (air) by the combustion of fuel, and deriving shaft energy from gases expanded through a turbine. High shaft velocities have been the rule with gas turbines, while useable shaft power is at velocities in the lower ranges; and all of which has made prior art gas turbines impractical and/or restricted in use. It is an object, therefore, of this invention to provide a low speed high torque gas turbine, wherein output shaft velocities are reduced while high torque is maintained With the present invention, the turbine operates at lesser velocity than the compressor driven thereby, the shaft output of energy being taken from the slower turbine operating within the high velocity flow of expanding gases.
Prior art turbines have utilized the separation of cooling air, taken from a primary fan and used to maintain sufficiently low operation temperatures. Heretofore, this cooling air has been expended; however it is an object herein to maintain compression of a diffused and separated column of compressor air, firstly used for cooling, and secondly combusted with fuel for the added use of heat energy. With the present invention, the primary stage of the compressor is followed by a diffuser which separates the working fluid into two columns that are sequentially carbureted or fuel injected and proportionately recycled and combined for thorough burning of the fuel used in the engine cycle.
An object of this invention is to proportionately recycle the combusted working fluid with added fuel, by means of which thorough and substantially complete combustion takes place. With the present invention there is an exhaust diffuser and a tubular turbine shaft that cooperate to recycle a determined proportion of the combustion gases, and accordingly it is also an object of this invention to advantageously utilize these heated gases and the aforementioned external column of cooling air by confusing the same as a secondary working fluid into which fuel is injected, and all of which is merged with the primary working fluid for the burning thereof.
Another object of this invention is to provide for the recompression of recycled combustion gases comingled with said external column of cooling air that is heated by a combustion diffuser that separates the cooling air from the combustion gases. With the present invention, the cooling air and proportion of recycled combustion gases are confused and accelerated while being carbureted or fuel injected for subsequent comingling with the primary working fluid, a working fluid distributor being provided for the functions of recompression and comingling of the primary and secondary working fluids. Recompression is achieved by imparting high angular velocity to the confused fluids and by directing them radially outward and then rearward at a pressure and temperature commensurate with that of the primary working fluid.
Turbines which have fans for the external flow of air involve speed reducers driven by a high velocity compressor-turbine. However, it is an object of this invention to provide a low velocity turbine and combine therewith a high velocity compressor with no fan, in which case a speed increasor is interposed between the compressor and turbine, driving the compressor at high velocity. With the present invention the normal rate of compression and the high velocity of gases are maintained, but at lower R.P.M. as compared with prior art turbines With the present invention, multi stage turbine blading commensurate with the required low velocity of rotation is employed to absorb the energy derived from the burning of fuel in the working fluid.